Fatigue Severity Scale (FSS)

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Tool Description

  • Originally developed for use among individuals with Multiple Sclerosis
  • Captures the individual’s experience of mental or psychological fatigue and how it interferes with performing certain activities (exercise, work and family life).

ICF Domain:

Body Function – Subcategory: Mental Function.

Number of Items:

9

Brief Instructions for Administration & Scoring

Administration:

  • Self report scale.
  • Participants choose the level of agreement for each question, from 1 = strongly disagree to 7 = strongly agree.
  • Ratings are based on their experience of fatigue over the past seven days.
  • The scale takes approximately 5 minutes to administer.

Equipment: None

Scoring: Sum the score from each item to get a total score.

Interpretability

MCID: not established for the SCI population, but for a rheumatoid arthritis sample [N=61, mean (SD) age: 62.1 (14.8) yrs, 9M/52F]

Regression-based MCID = 20.2
Standardized MCID = 0.74

Reference: Pouchot J et al. “Determination of the minimal clinically important difference for seven fatigue measures in rheumatoid arthritis” J Clin Epidemiol. 2008 July; 61(7): 705–713.

SEM:
SEM for total FSS (calculated from data in Anton et al. 2008): 0.56

MDC:
MDC for total FSS (calculated from data in Anton et al. 2008): 1.55

  • Scores range from 1-7 with higher scores indicating higher levels of fatigue.
  • Scores of 4 and over are indicative of significant fatigue in other populations, such as multiple sclerosis.
  • No cut-points or normative data have been established for the SCI population.
  • Published data for the SCI population is available for comparison (see Interpretability section of Study Details sheet)

Languages:

English, German, Turkish and Norwegian.

Training Required:

None.

Availability:

Freely available online; can be located at: https://www.saintalphonsus.org/documents/boise/sleep-Fatigue-Severity-Scale.pdf

Clinical Considerations

  • The FSS might have difficulties distinguishing fatigue from depression (the influence of pain may influence scores on the FSS)
  • Can be used as a screen for fatigue in individuals with SCI. However, results should be interpreted with caution as some items may not have meaning for the SCI population.
  • Some of the items may not be reflective of the SCI condition. However, the FSS has been extensively validated in other populations and may be the most widely used measure of fatigue in neurologic disorders.

Measurement Property Summary

# of studies reporting psychometric properties: 8

Reliability:

  • High Test-retest Reliability (2 weeks):
    Total ICC = 0.84 (95% CI = 0.74–0.90)
    Items ICC ranged from 0.32-0.77

(Anton et al. 2008; n=48, 31 males, motor complete SCI, tertiary care)

  • High Test-retest Reliability (2 weeks):
    Total ICC = 0.78-0.89

(Gavrilov et al. 2018, N=85 (MS patients, 32M, 53F), Mean age (SD): 37.6 (10.2))

  • High Internal Consistency:
    Cronbach’s α = 0.88-0.96

(Anton et al. 2008; n=48, 31 males, motor complete SCI, tertiary care)
(Gavrilov et al. 2018, N=85 (MS patients, 32M, 53F), Mean age (SD): 37.6 (10.2))

Validity:

  • Moderate ROC Analysis:
    Area under the curve = 0.799

(Anton et al. 2008; n=48, 31 males, motor complete SCI, tertiary care)

  • Low to High correlation with Fatigue Impact Scale:
    FIScognitive: r=0.35, P=0.001
    FISphysical: r=0.82, P<0.001
    FISpsychosocial: r=0.75, P<0.001

(Gavrilov et al. 2018, N=85 (MS patients, 32M, 53F), Mean age (SD): 37.6 (10.2))

  • Not Ranked
    Odds Ratio (95% CI) = 1.69 (1.09-2.29)
    X2 = 3.23; p-value = 0.07

(Craig et al. 2015; n=88 (62 males, 26 females); mean age (SD): 42.6 (17.8); 39% Tetraplegic, 61% Paraplegic)

Responsiveness:

No values were reported for the responsiveness of the FSS for the SCI population.

Floor/ceiling effect:

No values were reported for the presence of floor/ceiling effects in the FSS for the SCI population.

Reviewer

Dr. Ben Mortenson, John Zhu, Jeremy Mak, Gita Manhas

Date Last Updated:

July 20, 2020

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Download Worksheet:

Worksheet Document

Video

n/a

Scoring

Sum the score from each item to get a total score.

  • Scores range from 1-7 with higher scores indicating higher levels of fatigue.
  • Scores of 4 and over are indicative of significant fatigue in other populations, such as multiple sclerosis.

Equipment Needed

FSS:

Anton HA, Miller WC, Townson AF. Measuring fatigue in persons with spinal cord injury. Arch Phys Med Rehabil 2008; 89: 538-542.
http://www.ncbi.nlm.nih.gov/pubmed/18295634

Craig A, Perry KN, Guest R, Tran Y, Middleton J. Adjustment following chronic spinal cord injury: determining factors that contribute to social participation. British Journal of Health Psychology 2015;20:807-823.

Gavrilov YV, Shkilnyuk GG, Valko PO, Stolyarov ID, Ivashkova EV< Ilves AG, Nikiforova IG et al. Validation of the Russian version of the fatigue impact scale and fatigue severity scale in multiple sclerosis patients. Acta Neurol Scand, 2018;138: 408-416.

Hammell KW , Miller WC, Forwell SJ, Forman BE, Jacobsen BA. Fatigue and spinal cord injury: a qualitative analysis. Spinal Cord, 2009; 47(1):44-9 (Epub 2008).
http://www.ncbi.nlm.nih.gov/pubmed/18542089

Krupp LB, LaRocca NG, Muir-Nash J, Steinbery AD. The fatigue severity scale. Application to patients with multiple sclerosis and systemic lupus erythematosus. Arch Neurol. 1989; 46: 1121-3.
http://www.ncbi.nlm.nih.gov/pubmed/2803071